Scissor lifts are mechanisms used in commercial and industrial settings to safely and easily elevate a work platform to a desired height. Most scissor lifts include at least two sets of paired "arms". The arms are pivotably joined to each other at their ends and midpoints to create an extendible linkage. In order to extend the range of the scissor lift, multiple pairs of arms can be connected end-to-end. By expanding or contracting the distance between the ends of the lowest set of arms, the total height of the extendible linkage is increased or decreased.
A work platform is typically mounted on the uppermost pair of arms. The work platform and extendible linkage may vary in size and strength depending upon the foreseeable load bearing characteristics of the scissor lift. Frequently, scissor lifts can support more than one person and extend over thirty feet in height.
During the raising and lowering of a scissor lift, the pairs of joined arms comprising the extendible linkage pivot with respect to one another at numerous pivot points. These pivot points are located both where the ends of the arms join one another, as well as at the midpoints of the arms. Each of these pivot points are potential "pinch points" where the potential exists for pinching body parts or objects between two arms. Even a relatively simple scissor lift can have over a dozen pinch points.
During use, the operator of the scissor lift is typically positioned up on the work platform, and may not always take a careful visual inspection to assure that no one is in a dangerous position with respect to the lift arms. The operator may also find it difficult or even impossible to watch each one of these pinch points at the same time when lowering the scissor lift. When an operator is controlling the movement of the lift apparatus from on top of the platform, it can be very difficult to see over the edges sufficiently to view all pinch points and ascertain that nobody will be pinched. When an operator is controlling the movement of the lift apparatus from below, similar difficulties arise due to the large number of potential pinch points, as well as the possibility of a view obstructed by the lift arms as they are being lowered.
Severe injury may result to body parts at the pinch points during lowering of the scissor lift. For example, the operator, or an observer may have fingers, hands, or arms crushed or even severed. In the case of the most severe injuries, lifelong debilitation or even death may occur. In addition to the pain and suffering inflicted upon the injured person, tremendous costs can result from lost wages, rehabilitation, retraining, etc. The cumulative personal and economic costs associated with such injuries can be very high.
In addition to the potential for injury to operators and observers of the scissor lift, damage to the scissor lift itself or to objects positioned near the scissor lift is possible.
The hazards associated with using scissor lifts have been recognized by industry groups such as the Scaffold Industry Association, which has prepared standards for the design, manufacture, maintenance, and use of lift platforms. The Scaffold Industry Association has also welcomed proposals for improving safety standards for scissor lifts.
Many scissor lifts are currently in use, and the majority of these do not include safety guards. In order to improve the safety of such scissor lifts, a retrofitted guard must be installed on the scissor lift. In retrofitting these scissor lifts, the guard must be able to be installed on an existing scissor lift with a minimum of effort and expense. Also, the guard is preferably removable for maintenance on the lift apparatus or on the guard itself.
Accordingly, there is a need for a guard preventing pinching between the arms of a scissor lift. Even further, there is a need for a guard that can easily be installed on existing scissor lifts, as well as included with newly manufactured scissor lifts.